FIELD OF THE INVENTION
The invention relates to a sheet gripper in a sheet-fed rotary printing press, wherein a spring applies a holding force between gripper fingers and a gripper pad of the sheet gripper.
A sheet gripper of this general type has become known heretofore from U.S. Pat. No. 4,947,748 wherein there is shown and described a sheet gripper element or finger cooperating with a gripper pad. The gripper element is pivotally supported by a gripper housing therefor on a likewise pivotable shaft. In the immediate vicinity of the gripper element, a counteracting stop is secured to the shaft and is operatively connected to the gripper housing by a compression spring. The compression spring is disposed in prestressed condition between the gripper housing and the counteracting stop, so that when the gripper element meets the gripper stop, the full force of the prestressed compression spring comes into effect.
An impact resulting from this encounter can cause the gripper element to spring back from the gripper pad when processing speeds are high, thereby impairing a true-register holding or retention of the sheet that is to be transported. Furthermore, the cylinder carrying the sheet gripper is excited to vibrate.